Many stacking devices are used to continuously create stacks of sheet products. In one common stacking device, the sheets are fed from a feeding system to the top of a wheel that is rotated about a wheel axis. The wheel includes a plurality of spiraled wheel blades or fins that project in a direction opposite to the direction of rotation. The sheets are fed between two adjacent fins and are rotated within the wheel to a lower position where the paper is stripped from the wheel by a barrier. The stripped sheets fall away from the wheel onto a stacking plate located at the bottom of a stacking box. Different separators have been developed to separate two adjacent sheets being discharged from the wheel. The two adjacent sheets include a sheet that completes the stack of a specified number located in the stacking box and another sheet that begins a new stack on the separator.
For example, some stacking devices rotate a separator about an axis that is displaced from the wheel axis but within the periphery of the wheel. The separator is rotated into a position between a first fed sheet that has just been fed into the wheel and an adjacent second sheet that will be fed into the wheel behind the separator as the wheel and separator rotate in the same direction. The separator rotates to the stacking position where the separator allows the first fed sheet to complete the stack located in the stacking box and supports the second fed sheet to begin a new stack at a position above the stacking plate of the stacking box. The separator accumulates additional sheets of the new stack to allow the completed stack to be sent to downstream operations, such as a packaging or bundling unit. When the stacking plate of the stacking box is cleared and ready to receive the new sheets accumulated by the separator, the separator rotates through the stacking box causing the sheets to fall onto the stacking plate located at the bottom of the stacking box.
In the above-described device, the separator can strike the sheets that are not fully seated between the blades because the travel path of the separator intersects with the travel path of the blades. This undesirable contact is caused by rotating the separator about a different rotational axis than the wheel axis which causes portions of the path traveled by the separator to intersect the path traveled by the sheets carried on the wheel.
Another type of conventional stacking device rotates a separator about the same axis as the wheel axis. The separator is coupled by an arm to the wheel axis, however the separator is at all times located outside a cylindrical volume that is defined by the periphery of the wheel. The separator rotates to a stacking position between a first sheet has been discharged from the wheel into the stacking box and a second sheet that is still located within the wheel. The separator allows the first sheet to fall to complete the stack located on a stacking plate in the stacking box while the separator supports the second sheet above the completed stack as it is discharged from the wheel. The separator will support additional sheets while the stacking plate moves the completed stack to another location. The separator is limited to supporting only as many sheets as space permits because the separator is located a fixed distance from the periphery of the wheel. After the stacking plate returns to the stacking box and the stacking box is ready to accept the partially completed stack from the separator, the separator is rotated about the common axis. As the separator is rotated the barrier will strip the sheets from the separator and the sheets will fall onto the stacking plate that is located at the bottom of the stacking box.
Another type of conventional separating device includes a separator that rotates about the wheel axis and moves radially away from the wheel axis once it is in the stacking position in order to accumulate additional sheets. The separator is rotated into a position between a first sheet that has just been fed into the wheel and a second sheet that will be fed into the wheel behind the separator as the wheel and separator rotate at the same speed about the common axis. The separator is rotated with the wheel until the separator is located at the stacking position beneath the wheel. The separator allows the first sheet to fall and complete the stack positioned on the stacking plate of the stacking box and supports the second sheet to begin the new stack on the separator. The separator finger moves radially away from the wheel to support additional sheets. Moving away from the wheel creates additional space to allow the separator to support more sheets than would be possible with a separator that did not move radially from the wheel. The stacking plate therefore has more time to move the completed stack because the separator can support an increased number of sheets before they must be transferred onto the stacking plate of the stacking box. When the stacking plate returns to the stacking box and is ready to accept the stack from the separator, the separator will rotate causing the barrier to push the sheets from the separator. The sheets then fall onto the stacking plate that is located at the bottom of the stacking box.
Separators that are rotatably connected to the wheel axis often require a complex design that is limited in space about the axis of rotation of the wheel. The complexity of this configuration increases the cost of manufacturing and assembly costs associated with the separator. Inaccessibility of the components of such an intricate and compact design also tends to increase the maintenance and repair costs of the separator.
In light of the above design requirements and limitations, a need exists for an apparatus that discharges sheets from a starwheel assembly which provides a separator that controllably moves between two adjacent sheets within the wheel without adversely affecting the position or movement of the sheets within the starwheel assembly, provides a separator that moves efficiently to enable the use of a simpler and less costly design, and provides a separator that is mounted to the frame outside of a cylindrical volume that is defined by the periphery of the wheel to simplify the design and manufacture, thereby minimizing manufacturing costs, maintenance costs, and repairs costs. Each preferred embodiment of the present invention achieves one or more of these results.